6
Growing and caring for trees
We British are great tree planters. Our woefully denuded countryside was down to 5% tree cover 100 years ago, now it is more than
double that thanks to planting. Our success and experience makes
us a world leader in sympathetic planting – virtually all our state
forests are certified1 – though many wouldn’t have said that 50
years ago when we were coniferising ancient woodlands and
plastering hills with square blocks of dark green spruce! Our
history of planting goes back many centuries: we have all surely
heard how in the 17th and 18th Centuries the cry was to plant oaks
because the navy was running short of shipbuilding timber.
This is a long chapter and I’ve divided it into four sections to
look at:
how to plant trees and create a wood;
how to encourage trees to develop from natural seeding –
what foresters call natural regeneration;
. what may need doing as a stand of trees develops – cleaning,
pruning, thinning, felling; and
. coppicing and pollarding.
.
.
1
Certifying of forests first began about 10 years ago and is an independent
vetting that management meets agreed standards of good practice to ensure
sustainability.
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Growing and caring for trees
PLANTING A WOOD
Planting trees – the basics
In the Bible the Teacher proclaims: ‘‘There is a time for everything,
and a season for every activity . . . a time to plant, a time to uproot
. . . ‘‘ (Eccl. 3.1–2). So what are the questions we need to cover to
know that it is a ‘good time to plant’?
Where to plant trees
An odd question to begin with, but are there spots or places to
avoid? I ask this first because visitors to my wood who see gaps,
from a recent thinning or creation of a glade, often assume that
tree planting is now needed: it isn’t. Generally we are overly keen
to fill up ground. Remember that existing trees need space to grow
and wildlife thrives in gaps and glades. More specifically do not
plant trees that might damage valuable habitat such as wetland or
right next to streams and, similarly, not right beside rides and
roads. If you do plant up a large opening, only plant trees in the
middle where there is clear sky overhead; young trees don’t grow
well in the shade of old ones.
So, plant trees to turn a field into a wood or as a way of
regenerating a large patch that has been clear felled, otherwise
think hard about whether your really need to.
As an aside, if you need to add trees to a hedgerow, try
recruiting a sapling by not cutting it when hedge-trimming. Make
sure the sapling is growing directly above where it is rooting to
avoid developing a ‘S’ bend and remember to mark the sapling
with a stick or ribbon so whoever is trimming the hedge can see it
easily.
What species to plant
In Britain we have three native conifers and about 30 native
broadleaves. Introductions from across the world in the last 300
years have added immeasurably to the possibilities. In the
appendix there is a list of the commoner species, what they are
good for and the conditions that best suit them. If in doubt consult
a local forester, though usually Forestry Commission staff will be
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Badgers, Beeches and Blisters
happy to make suggestions, and do see what is growing well
already in or near your wood. You will rarely go badly wrong by
continuing to grow what is doing well in the vicinity.
Where can small trees be bought?
Contact a tree or forest nursery, not a garden centre. There are
many nurseries and your nearest will not be too far away. In the
Yellow Pages they are entered under ‘Nursery Horticultural –
wholesale’ and/or ‘retail’. When choosing a nursery make sure
the advertisement mentions trees, then phone them and go over
to see what is on offer, or visit the website or request a catalogue
and ask for a quotation for what you seek. Most nurseries like
orders well in advance and then they lift the plants you want –
‘plants’ are what the trade calls small trees suitable for planting –
and dispatch them to you just before the date they are to be
planted. Sometimes plants will be lifted in November or
December, carefully packed in bundles in purpose-made double
skinned polythene bags, and then kept in a cold store for dispatch
in late winter or early spring. The best thing is to contact your
local nursery as early as possible in the autumn to discuss your
requirements.
If you like the idea of developing your own small tree nursery
there is plenty of advice in books. We will look at the subject
briefly a little later.
What size of plants are best?
Usually it is the smaller the better. A plant 20–30 cm tall and 5–
7 mm thick at the root collar i.e. at the point where stem and roots
meet, will readily become established and start growing well once
the weather warms up, provided of course it is protected from
browsing damage and vigorous weeds.
Bigger trees, such as whips, saplings, half-standards (*3 m
tall) and standards (>3 m tall), all impose increasing strain on the
newly inserted root system. Their crowns of leaves demand
many litres of water each day which the roots cannot easily
deliver because many were broken off, especially the fine roots,
when the trees were lifted from the nursery and because they
haven’t had much chance to re-grow in the new soil. Not
surprisingly, large trees planted for effect on housing estates can
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Growing and caring for trees
languish for years with thin crowns and poor leaves. Worse,
large trees are one hundred times more expensive, and I’m not
exaggerating.
What kind of tree to plant?
Seedlings and transplants are the two commonest names you will
come across in a nursery catalogue. When they are sold no soil
attaches to the roots, so they are called ‘bare-rooted’ plants. We
will define them along with some other types of plants.
Seedling This is a plant that has grown up from seed, but has
never been moved in the nursery until it is lifted for dispatch after
it has been sold. Seedlings are usually one or two years old and
15–50 cm tall.
Transplant This plant began life as a seedling but was moved,
when dormant, from one nursery bed to another, hence the name
‘transplant’. The moving between beds severs tap roots and helps
ensure a stocky, more robust, plant with a compact root ball. They
are the commonest type of plant used and are mostly 2–4 years old
and 15–75 cm tall.
Undercut This plant is a seedling that has had its roots undercut
in situ at a depth of 10 or 15 cm to achieve the same effect as
transplanting but without moving it from one bed to another. They
are usually 1–3 years old and 15–75 cm tall.
Whips Plants that are allowed to grow beyond the seedling/
transplant stage for another one or two years in the nursery to
reach 80–150 cm tall. If well furnished with branches, they are
known as ‘feathered whips’.
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Some of the types of plants/trees for sale at a forest nursery (not to scale)
(i) transplants
(ii) container grown tree
(iii) cutting (typically of poplar), and after it has become rooted
(iv) feathered whip
(v) half standard
In a nursery catalogue the type of plant and its age is indicated
by a simple code. A seedling is just given an age. A transplant may
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Growing and caring for trees
be shown as 1þ1 meaning it is two years old, having grown one
year as a seedling and then been transplanted to another bed for a
further year. If it grew for two years in a transplant bed the
catalogue shows this 3-year-old plant as 1þ2. An undercut is a 1u1
if it grows as a seedling for one year, was then undercut, usually in
about June of the second year, before being sold. Sometimes
undercutting is done during the first season in July and one year
old plants and are shown as 1=2u1=2, but are seldom sold.
Container-grown stock Growing small trees in containers is quite
common. It gives each plant a root ball and is used for trees, such
as birch and Corsican pine, which lack fibrous roots to improve
establishment. In general, forest trees are bought as bare-rooted
stock. There are many kinds of containers and many names for
them: containerised stock, Japanese paper pots, cell-grown stock,
plant plugs raised in pre-formed plastic trays, pot grown stock,
and ones raised in a hinged ‘book’ such as ‘Rootrainers’. Container
grown trees are more expensive, typically twice the cost per plant
of bare-rooted ones. Many nurseries do not stock all tree species in
this form.
Plant quality
So far we have considered what type, what size and from where
plants can be obtained, but what about quality? It is important for
plants to be sturdy to survive the rigours of planting whatever the
site. Although height of plants is commonly given in catalogues,
root collar diameter i.e. how thick it is at the point where stem and
roots meet, is more important. Research shows unequivocally that
thickness of stem, not how tall a plant is, is the most reliable
indicator for subsequent survival after planting. Basically one
wants healthy plants that have thick root collars, not weak flimsy
ones. Equally important is a vigorous, fibrous root system, not a
single long tap root.
The plants themselves must be free of damage, disease and
other defects.
When plants arrive
Forest plants (young trees) are dispatched in special, double
skinned, polythene bags which are black on the inside, sealed and
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Badgers, Beeches and Blisters
designed to minimise heating if ever exposed to the sun, even if
briefly. On receipt of your plants, open the bag and check that the
right species have been sent and that the specifications are as
ordered. Then take one or two plants from a few of the bundles –
transplants are typically in bundles of 25 or 50 – and check their
health by nicking the bark on the stem with your thumbnail. The
tissue beneath should be green or greenish-white. If it is at all
brownish then the plant is likely to be dead even if the buds and
other parts look OK. If more than one or two are brownish, reject
the entire consignment and complain to the nurseryman.
Once you are happy with the plants – they are what you ordered
and appear healthy – gently retie the bundle and close the bag.
Store the bag(s) in a cool, dry place, preferably in the dark or in
heavy shade, and make sure it is frost-free. An unheated garage is
ideal provided it never cools to below freezing. While dormant in
winter and early spring, such plants will remain alive for many
weeks. Normally plants will stay damp enough in the bag they
came in if it is kept sealed until time for planting.
Try not to move the plants until the day of planting. In
particular DO NOT manhandle the bags, NEVER throw them
around or drop them: treat them like your finest dinner service!
The fine roots of young trees are easily broken and damaged, but
this is rarely obvious to see. Experiments by the Forestry
Commission show that bags with bundles of plants that are
dropped, even from a height of only one metre, reduced the
survival of the young plants when planted out. The more frequent
the dropping and mishandling the worse survival and growth
became. The take home message is: handle with care.
Obtaining trees for planting need not be an expensive business.
A little forethought and care of the plants received is all that is
required.
When is the best time to plant?
Plant trees anytime from mid-autumn to mid-spring, but avoid
very cold and frosty weather. In the south of Britain all planting
should be done by the end of March, in the north by mid-April.
Trees must be planted while they are dormant and before they
start coming into leaf (flushing).
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Growing and caring for trees
How far apart should trees be planted?
Usually trees are planted 2–3 m apart and equidistant along and
between rows i.e. square spacing. You mark the position with a
stick, or if planting only a few trees judge the distance
approximately by pacing. There’s no need to lay out a new
wood or a belt of trees with the ‘theodolite’ precision seen in many
an orchard.
If you are planting a thick hedge, three rows are a good idea and
use triangular spacing. Set the trees about one metre apart.
How is planting actually done?
While a nicely dug pit is best, a simple slit in the ground with a
spade or mattock is often sufficient. Gently place the roots in the
slit or pit and tease them out. Then, while holding the tiny tree
vertical, replace soil and firm it home with the ball of the foot.
Make sure that the tree is planted only to the depth of the root
collar, neither deeper nor shallower.
John White’s idea of my brother-in-law and me planting trees in my wood –
plus fours are not de rigueur
It is sometimes recommended that broken or damaged roots are
trimmed with secateurs before planting. This takes time, is
probably of little benefit and the further handling of the tender
root system will break off more fine roots. The only time trimming
will help is where roots are long and straggly since it’s no good
simply stuffing everything into the ground.
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Do I need to stake my trees?
No is the short answer, unless the trees are over 2 m tall – which is
not recommended. If staking has to be done, use a short one and
secure the tree at about 30 cm from the ground. Do not fasten a tree
to a stake at 1.2–1.5 m; the tree needs to flex from the base to build
its stem properly. All a stake does is to help anchor the root
system. Do remember to loosen the tie each year. By the third year
a stake should no longer be needed.
Do trees need fertilising and irrigating?
In general, ‘no’ to both questions. If tree planting is done properly
neither fertiliser nor irrigation will be needed. Phosphate (P) may
help on some poor upland sites or sandy soils, but elsewhere the
soil is already fertile enough for the undemanding appetites of
trees. If you’ve planted the trees properly in the autumn or early
spring and provided competing weeds are under control, you
shouldn’t need to water them in the summer however hot and dry
it gets. Only large trees such as half-standards may need irrigating
just to keep them alive, but you know what I think about such
planting stock already!
A summary
The key points are:
.
.
.
.
.
.
56
generally use small, thick-stemmed plants bought from a
reputable forest nursery;
make sure plants are alive and healthy – a thumbnail nick of
the bark should reveal greenish tissue;
always keep plants cool, shaded and prevent roots from
drying out – treat them gently;
plant trees while still dormant and before starting to flush i.e.
by the end of March;
plant during cool, damp weather and not when it is frosty or
very dry;
plant the tree by inserting roots carefully into a small pit or
slit in the ground and gently firm the soil with the ball of the
foot.
Growing and caring for trees
What happens next?
So, after the planting, what then happens? Put another way, how
are newly planted trees looked after during their first few months
and years? There are really only two main concerns: protect them
from damage, and don’t let weeds get the upper hand.
What threatens young trees?
Young trees are vulnerable to several dangers. Particularly
damaging are browsing animals, such as rabbits, hares, deer or,
indeed, livestock. If they are present newly planted trees must be
protected. Some of these animals will also gnaw or strip bark.
Protection from late spring frost, drought or strong winds are
largely outside one’s control. Overcoming frost and drought
problems is mainly resolved by choosing hardy species to plant
and, for example, not planting in a frost pocket or on thin soils that
readily dry out. Protection from insect pests and diseases is
usually not needed. There is a nasty weevil that costs owners of
commercial forests a lot of money to control, called Hylobius abietis.
It has a predilection for the bark of very young conifers (and other
species), but it usually isn’t worth doing anything about it when
planting only a few trees and, anyway, on many sites it doesn’t
cause any damage at all.
How do I stop animals causing damage?
The main choice is between fencing or individual tree protection.
For individual protection there are many proprietary products to
choose from. All are variations on a theme of plastic tubes or
plastic mesh. The main consideration is the browsing animal itself
and the height it can reach. For rabbits and hares a 60 cm high
guard is sufficient, for roe deer 1.2 m, and for red or fallow deer
1.8 m. Very roughly, use individual guards if you need to protect
fewer than 1000 trees, but consider fencing if you’re planting more
than this in one block. The basic specifications for a rabbit and deer
proof fence are sketched here. Typically a contractor will charge
£5–10 per running metre to erect such a fence.
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Rabbit and deer proof fence showing typical specifications. You will only need this if you
are into serious planting. For small numbers of trees use individual tree protection
Smearing repellents on the growing shoot of a tree is a nice idea
though the only useful product is called ‘Aaprotect’. It lasts for a
few months but only affords protection to the parts of the tree
actually smeared. Synthetic lion dung and other seemingly
fearsome smells have been much hyped and, on the whole, found
much wanting!
I am going to insert here an aside about a topic that doesn’t fit
happily elsewhere in this small book: the control of an animal that
is the scourge of broadleaved woodlands – the grey squirrel. This
menace from North America strips bark from oak, beech and
sycamore trees (and many other species) and will attack trees as
small as the thickness of one’s arm to nearly mature ones. Damage
occurs mainly in May, June and July. If uncontrolled they can ruin
a promising stand of trees disfiguring and sometimes killing them.
Grey squirrels have been designated a pest since the 1930s. They
are controlled by poking their nests (dreys) and shooting animals
that emerge, by trapping them, or by poisoning with warfarin. The
law is strict about what can and cannot be done. Even if you like
grey squirrels in your garden, they are no friend in your wood.
They damage your trees, probably raid birds nests for eggs, and
may harm other wildlife.
Now back to your newly planted trees.
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Growing and caring for trees
When should such protection start?
On the day you plant your trees! All too often planting has been
done one day with the intention of installing protection the next
only to find devastation occurs that very night. Animals familiar
with a territory soon know that new and succulent plants have
arrived – there is some evidence that freshly planted material
actually emits chemicals that can be sensed. Some years ago I
planted six fine young cherry trees in my wood and I thought I
could get away without protecting them. Within twenty-four
hours each was sought out and nibbled or bark stripped. Don’t
wait for damage before giving protection.
Do I need to worry about competing weeds?
Yes, this is important since weeds compete with young trees for
moisture and nutrients and, if they grow tall, for light as well.
Some weeds such as wild clematis and wild honeysuckle will also
entwine and even overwhelm saplings.
How are weeds controlled?
Weeds are best controlled by killing them either with herbicide, by
applying a mulch (a material placed on top of weeds to suppress
them), or by hoeing around the tree. Just cutting weeds is
ineffectual. Many owners of small woods will not want to or really
need to use herbicide, particularly if you have willing labour to
hand! If you do go down this route, use a proprietary herbicide,
such as round-up (glyphosate), but take great care to avoid any of
the herbicide getting on to the tree. If weeds were got rid of before
planting, one application of herbicide in late June or early July will
usually be sufficient to kill weed regrowth that has developed. Do
read the label for instructions and follow them to the letter.
Herbicide can be applied either with a directed spray or wiped on
with a device that has a wick moist with the herbicide.
A good alternative to herbicide, particularly if you only have a
few trees is to use mulch. Many materials are suitable, such as bark
chips, black plastic, and even old carpet placed around the tree.
Make sure that inert mulches like black plastic are thick enough
e.g. farm silage wrap, and well pegged down. Organic mulches
should be 6–10 cm deep; a light mulching is useless as weeds
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simply grow through. One attractive combination is to use plastic
sheeting as the main mulch and then sprinkle bark chippings on
the surface both to keep it in place and as a disguise. Mulching is
best done at the time of planting.
Cutting or mowing weeds is not very effective in relieving stress
to young trees. Although cutting reduces competition for light, it
usually worsens it for moisture and nutrients as new weed growth
with new demands is stimulated. Just think of a lawn: for as long
as it is kept green by mowing it is necessarily drawing moisture!
How far from a tree should weeds be controlled?
Control weeds to a distance of about 60–70 cm from the young tree
or a diameter of 1–1.5 m. There is no need to kill all weeds between
rows of trees, just concentrate on controlling those immediately
around the tree itself.
How long will weed control be necessary?
Continue weeding until the tree is about 2 m high. This will
usually be for about 3 years, and one weeding per year, provided
weeds are killed, will usually be sufficient.
Do I need to replace trees that die?
Not necessarily. Since over the life of a stand of trees one will
usually thin them out at intervals, it is not necessary to replace
every tree that fails in the first year or two after planting. A rule of
thumb is to replace failures if more than one in five dies. Less than
this, and the odd death doesn’t matter.
Starting trees from scratch – Seeds, Seedlings and Tree nurseries
As we’ve noted, most trees start life as seeds sown in a special
forest nursery where they are cared for until robust enough to
withstand planting out on the site where they will spend their life.
This is very different from growing corn or cultivating vegetables
where a seed is usually sown in the place where the plant is to
grow. However, sowing tree seeds directly on a site to be
restocked can sometimes work.
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Growing and caring for trees
Sowing seeds directly
One can be tempted to find one’s own seeds – acorns, beech nuts,
seeds that fall out of a dry pine cone etc. – to sow directly into the
soil; after all even 30–50p per plant from a nursery sounds
expensive when wanting to plant hundreds of trees. But sowing
directly is more difficult than it might appear and I list the reasons
why, as a reminder of what we need to think about when
establishing trees.
.
.
.
.
.
.
You can’t be sure seeds are viable and often only a few will
germinate
Some seeds such as those of ash need cold, moist stratification2 to germinate well
Sowing depth can be critical, neither too deep nor too
shallow, but this varies between tree species
Seeds are eaten by mice, voles, birds and squirrels and you
need to sow many times more than the number of trees you
hope to establish
Tender seedlings that do emerge are easily swamped by
other vegetation or may be browsed
Seedlings from seed sown in a wood generally grow much
more slowly in the early years than those from a nursery
For all these reasons it is far, far safer to buy and plant healthy
young trees, already 1–3 years old, that have been raised in a
special nursery with the care this affords. They will continue to
grow faster for several years than seedlings in a wood.
If one is anxious to save money at this stage, then dig up wild
seedlings, called ‘wildings’, from elsewhere in your wood and use
these. Do it properly by excavating a decent root ball and planting
the tree in the new location as soon as possible. It is time
consuming and, of course, one is restricted to what wildings are to
hand. You often find that such self-sown seedlings have astonishingly long, straggly roots that are difficult to dig up. Their lack of
fibrous roots slows establishment and early growth.
2
Stratification is the storage of seeds at just above freezing temperature in
damp sand or peat for several weeks or months to mimic winter soil conditions.
This ‘pre-chilling’ is required for species with deeply dormant seed to improve
germination when sown.
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Your own nursery
It can be enormous fun growing your own trees from seed. Your
friends can help too, sowing acorns in flower pots and bringing to
plant in your wood as trophies and trysts of friendship! But if you
want to grow you own seedlings for a significant planting you will
require a site which is quite demanding in its requirements, but
will often be met by the corner of the vegetable patch in your
garden! The key requirements are:
.
.
.
.
.
.
full protection from browsing animals – voles, rabbits, hares
and deer;
full protection from seed predators – mice, birds and
squirrels;
access to irrigation;
soil that is friable and easily worked and kept weed free;
a location that is not excessively exposed or a frost hollow;
adequate access.
If you have such a site and want to try your hand, I attempt to
do here for tree seeds the sort of instructions one finds on the side
of every flower or vegetable seed packet.
A few years ago The Tree Council issued an excellent booklet
entitled ‘The Good Seed Guide – all you need to know about growing
trees from seed’3. It is most helpful and well worth getting if you
want to grown your own. It is illustrated in colour and silhouette
images, many by John White who has illustrated this book as well
as the two telling the story of my own wood! In the booklet’s
information sources at the back, one cited is John Evelyn’s famous
Silva, published over 300 years ago, and that rather took my breath
away!
I will cover here the main topics in brief and content myself with
strongly recommending that you obtain the Tree Council’s
excellent guide.
3
The Good Seed Guide published by the Tree Council in 2001. ISBN 0-90485301-2 The Tree Council’s address is 51 Catherine Place, London SW1E 6DY
Tel: 0207 828 9928 Fax: 0207 828 9060 Website: www.treecouncil.org.uk
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Growing and caring for trees
Where to get seeds from
If you want to collect your own seeds, obtain them from several
different trees of the desired species not just from one, and from
trees that are healthy and of good form. You can also buy tree
seeds from certain nurseries. Whatever you decide, supplies of
seed from year to year are not consistent since most trees only fruit
heavily at intervals.
Sowing seeds
When – sow seeds in mid to late spring once risk of frost in past.
Condition of bed – prepare soil into a tilth, clean away all weeds,
incorporate a slow-release compound fertiliser high in phosphate
(P), but don’t over-fertilise.
Quantity – aim for 100 seedlings per square metre of bed or sow 2
or 3 per container.
Depth – sow small seeds, such as birch, on the surface and very
lightly cover, larger seeds, such as acorns, should be sown to a
depth of 1 to 11=2 times their longest dimension. They needn’t be
placed point upwards as they naturally germinate on their side.
Seed covering – cover seed to prevent birds eating them and help
keep them moist. Use sand or grit that is on the acid side of
neutral, not chalky. Sandy loam will do.
Watering – Irrigation is critical, but mustn’t be overdone. How
much depends on weather conditions: the bed or container soil
should neither be soggy nor dry and dusty.
Protection from mice and birds – Use netting to keep birds away in
the precious days and weeks between sowing and germination: a
cat might deal with both threats!
Germination
Germination of seeds never occurs uniformly owing to the seeds’
condition, the nature of the seedbed, and other factors not under
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one’s control. Germination time varies between species. Expect
some seeds to germinate a few days early, most to come up at
about the average time and a few to be slow and only emerge as
time goes on. There will be a definite peak when most come up. In
the days after germination provide shade if it is at all warm and
sunny since young seedlings are very tender.
Weed control
Seeds of weeds, by their very nature, often germinate quickly,
grow rapidly and soon overtop your tiny trees so they must be
helped at this critical phase. Pull up all weeds. Do this once a week
for the first couple of months and then as conditions dictate.
Thinning out and pricking out
When sowing flower or vegetable seeds we are used to thinning
out seedlings to give the remainder room to grow. This is less
common in tree nurseries except when using containers and you
only want one good plant in each. If you are thinning down to one
plant per container use the surplus seedlings to make good any
containers that are empty. This operation, a form of pricking out, is
best done when seedlings are small ‘matchstick’ size. Ease the
seedling from the container soil and straightaway re-pot it in the
new container using a miniature dibble, such as a small stick about
the thickness of your little finger with a pointed tip. No time
should elapse between lifting and re-potting the seedling apart,
possibly, from a brief dunking of the roots in clean water. Do the
work in the shade. These precautions are essential: it doesn’t
matter how careful you are as lifting and transplanting will break
off many fine roots – the tiny tender roots and root tips you can
only see with a hand lens. Without these the seedling will struggle
until they become re-established again in two or three days time.
Freshly pricked out and re-potted seedlings should be kept
shaded, but not in the dark, for a week, though the amount of
shade can be reduced after about three days.
Transplanting and undercutting
In a small nursery simply use an ordinary flat spade for
transplanting. Do it when the plants are dormant, between late
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Growing and caring for trees
Autumn and mid-Spring, but not when ground is frozen. Sever the
roots at a depth of about 15 cm and lever up the plant. Gently
shake the soil off, place the seedling in a polythene bag in the
shade, and replant it as soon a possible in its new bed for another
year’s growth. It is now a ‘transplant’.
To undercut, use a spade sharpened with a file. Angle the spade
down to cut the roots at 15 cm depth, and then withdraw.
Undercut in the growing season, say in July.
Lifting and despatch
Your baby trees are ready for planting, usually after one or two
years in the nursery when they are 15–50 cm tall and 5–8 mm thick
at the root collar, and the final job is to lift them. With a small
number of plants, simply repeat the transplanting operation to
extract them from the bed, gently shake off soil and place them
carefully in polythene bags kept in the shade. Provided plants are
dormant when lifted and are kept in a cool dry place – and not at
risk from frost – they can be stored for up to 2 months before use.
Now follow the operations for normal planting we outlined
earlier.
If all the above operations proceed as planned, you will have the
immense satisfaction of growing trees from the very seed you
collected. There is no surer way of being certain of their origin and
perpetuating the trees and shrubs you want to.
NATURAL REGENERATION
Most kinds of trees in Britain readily set fertile seed that falls or is
carried by wind or birds to become the next generation of young
trees. We all know someone whose lawn is seemingly invaded
year after year by sycamore seedlings or baby oaks germinating
from acorns, or how a patch of bare soil or a neglected corner soon
sport some healthy birch or ash. Such ‘volunteer’ trees are called
‘natural regeneration’. In our wood this free good is mostly the
occasional birch and ash, except on the south side where carpets of
sycamores have arisen thanks to seeds from a couple of large, old
specimens nearby.
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Badgers, Beeches and Blisters
A jay, the master of oak natural regeneration
But are free seedlings like this always welcome and when
should one utilise them? Firstly, the trees may not be growing
where they are wanted and there’s no point in encouraging trees
to grow simply to fill up some land. One can dig up such self-sown
trees and transplant them but, as mentioned earlier, you will find
that even small ones have roots that will have taken a strong hold
and often penetrate to a surprising depth. Experience shows,
however, that even with great care such ‘wildings’ often don’t
grow very well.
Secondly, not only may self-sown seedlings not be of the kind of
tree one wants but also they are not always found growing on a
site suited to them. A common example is ash which springs up in
dense thickets on many freshly exposed road and railway
embankments. Despite their profusion they will not develop
well on such sites and neither highway authorities nor, certainly,
Network Rail, will welcome them either!
Where natural regeneration comes into its own, is when one
wants to perpetuate the local tree stock, perhaps for reasons of
conservation. Using self-sown trees continues the line of the
parents and this goes back generations – centuries in the case of
some trees – and so is a genetic link with the woodland heritage of
an area. This is mainly a concern with native species and provided
the stock is adequate for all of one’s tree growing objectives.
Deliberately encouraging natural regeneration is tricky. As a
way of regenerating woodland it is attractive, but seeds may not
be available in the year you want to begin and even if there is
plentiful seed fall, it may not survive the ravages of scavengers
such as mice and grey squirrels. The ground needs to be prepared
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Growing and caring for trees
by light cultivation and you will need to control competing weeds.
Perhaps the best advice is simply to take advantage of any
regeneration that does appear rather than trying to make it
happen. Even experienced foresters can fail to regenerate stands
by natural means!
WHAT MAY NEED DOING AS A STAND
OF TREES DEVELOPS
Here we look at four silvicultural operations that a stand of trees
may require at some stage. They are not equally important. For
example, high pruning may only be needed for reasons of rideside
safety or if you hope to grow high quality timber.
Cleaning
Cleaning makes us think of washing clothes, tidying our homes,
scrubbing a work-surface, or polishing the car, but in forestry
parlance it has a special application. Cleaning is the job of
removing unwanted growth in a stand of young trees that’s past
the establishment phase but before trees are big enough to be
usable, say when 3–7 m tall. It is an operation that should follow
weeding but is commonly neglected although much needed in
young woodland. It is ideal autumn and winter work and can
be done reasonably safely with hand tools such as saws, hand
axes and billhooks, secateurs or pruners. Anything from a tiny
group of perhaps a dozen trees upwards will benefit from
cleaning.
Cleaning is all about sorting out a stand of young trees to help
those you want to succeed at a time when those not wanted are
small enough to be dealt with by hand. I thought the best way to
illustrate it is to reproduce an extract from Chapter 15 of my book
‘What Happened to Our Wood’. The chapter is called ‘Cleaning
Taid’s Wood’. I’ve added some headings for clarity.
The story so far
In 1987 my brother-in-law and I planted four acres of new
woodland with a mixture of ash, wild cherry and oak trees.
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We called it Taid’s Wood after my father. The trees grew
vigorously in their early years with each individually
protected by the then latest device, the plastic tubes or
treeshelters, that today litter so much of our countryside. The
treeshelters worked well, hardly any trees died and many
grew nearly a metre in height each year.
Sporadic removal of treeshelters began in the mid-1990s as
the cherry trees quickly swelled to fill the tubes. Removal of
all of them from Taid’s Wood began in January 1999. But,
once de-sheltering was complete, we rather neglected this
part of our wood.
The problems neglect of woodland can bring
Neglect can be damaging for broadleaved stands like ours.
Unlike most conifers, species like oak, beech, and ash often
fail to develop a straight stem unless deliberately helped by
the way the trees are grown and cared for. Straight stems
are encouraged by growing trees close together, to force
upward height and suppress heavy side branches by mutual
shading, by selecting trees of good genetic stock, or by
formative pruning. In Taid’s Wood although we had
planted the trees about 3 m apart, coppice growth of
sycamore and some hazel did in places provide the desired
more densely stocked conditions. But using other woody
growth runs the risk that it will dominate, and even
suppress, the planted trees. It’s like allowing moss to green
up bare patches of lawn only to find it takes over
everywhere. Thus a time comes when a stand of trees
needs sorting out, and the job is called ‘cleaning’. It brings
in no cash but lays the foundation for the future crop, and is
a job neglected at peril. In Taid’s Wood serious cleaning
began in the winter of 2000. The best ash and cherry were
already 10 m tall and the oak about 7m.
What the cleaning entailed
Initially, one is hesitant in deciding what to cut but over
several half days work, six distinct activities evolved. It was
like tidying the garage, the more one does the more is
discovered that needs attention and the whole job takes
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Growing and caring for trees
longer than intended. The main task in Taid’s Wood was to
cut regrowth of sycamore and hazel and self-sown birch and
sallow that competed with the planted ash, oak and cherry
trees. My small Stihl chainsaw, lightweight with a short 12’’
guide bar, proved ideal. Stem thickness rarely exceeded 3’’
and with a well sharpened chain the saw cut through in
seconds. With head down and felling several coppice stems
in quick succession a rhythm develops though at the risk of
being overzealous. Not only is there the question of safety,
but the need to consider carefully each stem to be cut, since
not every unplanted woody stem is necessarily unwanted.
With the fairly widely spaced trees there was still benefit to
be had from extra stems to make good any gaps and, in a few
places, to substitute the planted tree if it was poor. It was
important continually to keep an eye on the surrounding
trees where one worked and always on the look out to recruit
a new stem. Several well-grown sycamores were added in
this way. The grand object was to secure the future of all the
best trees and sometimes bring into the reckoning a new one.
By cleaning, an unmanageable thicket was turned into a
young stand of forest trees.
A few of the planted trees, although growing vigorously,
had such badly shaped stems or ungainly crowns of branches
that no amount of formative pruning would produce
anything worthwhile. These ‘wolf’ trees are best cut out
during cleaning. If not, they occupy much space and interfere
with better formed adjacent trees. Perhaps one ash in twenty
was culled – ‘de-wolfed’ – from Taid’s Wood and one in fifty
of the generally better cherry trees. None of the oaks was
really big enough to merit the de-wolfing epithet and also
they were being grown in a different way from the rest of
stand.
Tiny groups of oaks had been scattered throughout the
matrix of ash and cherry trees at 14 m centres with the
intention that oak will form the final crop. At each centre
three oaks were planted in a tight triangle with the idea of
selecting the best. A choice of one out of three for oak, with its
generally poor form, is really too few. I hoped to get away
with it because the acorns had come from good genetic stock
and the activities of cleaning and formative pruning at the
right time had been factored in. Assuming I was around,
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Badgers, Beeches and Blisters
Taid’s Wood for one would not be neglected! As cleaning
proceeded the triplets of oak were inspected and one or even
two of the trees cut out if there was already a clear winner.
However, for a few groups it was too late and all three oaks,
with their slower growth, were dead or nearly so, suppressed
by vigorous adjacent ash or sycamore.
All the while cleaning proceeded, the job was repeatedly
interrupted by the strings and ropes of Clematis that
entangled the undergrowth and ascended into the crowns.
Sometimes they stretched from tree to tree like rigging on a
sailing ship, but without the order and purpose, and would
prevent cut stems falling to the ground. The problem was not
serious since during establishment of Taid’s Wood killing
Clematis had been a priority. Nevertheless, dealing with this
temperate vine was a crucial part of the cleaning. Tough
stems, an inch across, were cut near the base and,
importantly, the climber itself was pulled down from every
tree it had assaulted. On one wintertime visit it was almost
fun. Ben, our youngest son, had come to help and took on the
climber-pulling task. It was the Saturday before New Year
when most of the country was still in the grip of snow and
ice. The trees in Taid’s Wood were not only gripped by
Clematis but still, albeit loosely, by Wednesday night’s snow.
Cutting any woody growth with the chainsaw sprinkled
snow but Ben, yanking and pulling down Clematis repeatedly
got showered! At least the snow did lubricate the branches so
that the whole vegetable mass slid off the tree quite readily,
and the hard work kept us warm.
The final cleaning task was to revisit all the better trees.
While several ungainly ‘wolf’ trees were felled, many ash and
a few of the cherry were forked or had heavy branches that
interfered with less vigorous but better formed neighbours.
Although the offending limbs were often rather large –
ideally pruning should be confined to branches less than 2 ins
across – removing them gave room for adjacent trees to
develop. When the first proper thinning takes place in a few
years time the future of these partially de-limbed trees will be
re-considered, and many will probably go. As with thinning,
the intensity of cleaning and what is removed is an open
question. Very thorough cleaning and removal of all the poor
trees, could make a lightly stocked stand decidedly gappy
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and moth-eaten. As with most forestry tasks today’s handiwork will be judged many years into the future.
Pruning
In woodland operations there are three situations when pruning
might be undertaken, but none is essential compared with pruning
roses, grape vines or fruit trees.
.
.
.
While cleaning a young stand of trees, singling a fork in the
main stem of an otherwise desirable tree is a pruning that can
be done with secateurs or long arm pruner.
For reasons of safety and good access, pruning branches
from ride and track side trees is commonly needed.
When growing high quality timber side branches are pruned
from the lower trunk to a height of about 4–6 m to restrict the
knotty core of timber. This is done early in the life of the
stand while the trunk is no more than 10–15 cm thick.
When to prune
In terms of season, pruning can be done at any time though it is
best to avoid late spring when copious sap flow can occur. For
walnut and wild cherry trees pruning must be done in June or July
to minimise disease risk.
In terms of size of tree, this will depend on the purpose listed
in the bullet points above. One rule-of-thumb is that it is best not
to prune branches bigger than 5 cm at the base, otherwise the
wounds take years to heal over and readily become infected and
start to decay.
How to prune
The aim is to sever the branch cleanly close to the stem. Do not do
this absolutely flush but angle the cut slightly outwards beginning
just outside the branch bark ridge – the zone of creased bark at the
junction of branch and trunk.
Special long-handled pruning saws do the best job since one
wants to cut through not tear the bark. Lopping with an axe is
dangerous and generally damaging.
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The pruning saw I use, it’s a superb tool
Use of sealants
Although painting a sealant over a pruning scar feels as if you are
providing a protective bandage, research has shown that little is
gained, either in preventing disease or hastening the callus that
heals over the wound. Spend time on doing the job carefully and
cleanly not money on proprietary sealants.
Thinning
This topic and the next one, felling, are touched on only briefly.
Both are major operations that require professional advice, trained
operators and are usually done by contractors. What I will do is
explain the idea and point you, I hope, in the right direction.
What is thinning?
At planting, or from natural regeneration, commonly two or three
thousand trees are established per hectare. Yet at the end of a tree’s
life – at its rotation age – 50 or 100 or more years later when it is big
and ready for the market, only 50 to 250 trees per hectare are left.
The process of reducing the stocking of trees down to this small
number is the operation of thinning. It is done at intervals as the
stand of trees gets older and older.
If you are wondering why one starts out with so many trees
when only about 10% are wanted at the end, there are three main
reasons: to occupy the available ground quickly; to provide a wide
choice of trees from which to choose the very best; and to prevent
individual trees developing thick, heavy branches and a spreading
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Growing and caring for trees
crown which happens if, in early life, they are spaced far apart
without competition from neighbouring trees.
How do you thin a stand of trees?
The grand aim is to remove the worst and leave the best. One cuts
out dead, dying and diseased trees and those of bad shape. Also
one tries to favour the best trees by opening up around them to
give their crowns space to grow.
If you open up a stand too quickly by thinning very heavily, the
remaining trees – the ones you are wanting to favour – will be
blown about, snap off and sometimes be uprooted. Thus it is usual
only to thin out (remove) about one-third of the trees in a stand at
each thinning.
When do you start thinning and how often is it repeated?
Thinning begins when trees are 10–12 m tall and are big enough to
sell for firewood or pulpwood. To begin with the operation is
repeated every 3–5 years but as the trees become large and nearer
to maturity the frequency of thinning is reduced to every 8 or even
10 years.
Does thinning earn money?
Yes, usually, but not a lot. Because trees are being cut out from
among others left standing, the operation is quite tricky and the
total amount of wood obtained per hectare may be only be 20–40
tons, thus merchants or contractors won’t pay a lot for thinnings.
Worse, when trees are small in the first or second thinning you will
be lucky to get any income at all since the cost of doing it may be
more than the trees are worth. However, by thinning you are
improving the crop for the future, so it is best to do the job when
you can and not wait in the hope of a better price round the corner.
Felling and starting again
In commercial forestry trees are felled at the end of the rotation.
Usually in Britain all the trees in a stand are felled at the same
time: this is called ‘clear felling’. It is a drastic change to your
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woodland but is the most profitable way if this is important. After
felling the ground is replanted unless natural regeneration is
present or can be expected.
Because clear felling is a sudden and total opening up, there is a
trend towards less severe forms of intervention. Most are covered
by a new term ‘continuous cover forestry’. As the name implies,
trees are felled and regeneration encouraged without completely
clearing the stand: some big trees are always left and a woodland
appearance is maintained. It is a more intensive system, requires
skill, and may be less profitable. One way is to fell small groups of
trees and replant in the middle of the openings, another way is to
thin heavily among the old trees and develop volunteer regeneration, whilst a third way might be to clear fell most of a stand but
leave sufficient old trees to give the appearance of continuous
cover, and so on. Which system will work best depends mainly on
the site and the tree species involved. Space does not allow more
details here. To illustrate the complexity, one can’t regenerate
woodland using small openings if the species concerned is ash or
oak, both of which require plenty of sunlight from an early age,
but it could work well with the more shade tolerant beech. That
said, trying to establish groups of trees in small gaps is usually
doomed to fail. A useful rule of thumb is that the minimum
diameter for a gap to be worth planting (regenerating) is 11=2 times
the height of adjacent trees.
If you think your trees are mature and your wood has reached
the time when it should be regenerated – or you simply want to
start again and leave your own mark on the wood – seek
professional advice. As I have said before, an hour of a
professional forester’s time will repay handsomely as alternatives
are presented and opportunities discussed.
COPPICING AND POLLARDING
Coppicing
These terms describe cutting a tree near ground level (coppicing)
or someway above head height (pollarding) – and so out of reach
of browsing animals – in order to use the shoots that emerge to
form the next crop. The words ‘coppice’ and ‘pollard’ are also
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Growing and caring for trees
nouns that name a crop or tree created in this way. Only
broadleaved trees can be coppiced with the famous exceptions
of redwoods, monkey puzzles, some cypresses, Chinese fir and
one or two tropical pines. Even with broadleaves, coppicing
potential and vigour varies. At every coppicing a few stumps die,
and species such as beech and common alder generally do not
sprout coppice very well. With beech it seems to coppice better in
the wetter west parts of the country. Certainly in our wood in
Hampshire I have been surprised how many stumps of beech have
coppiced following wintertime thinnings in 1997 and again in
2003.
Restoring an old coppice
I begin with this because if you have bought a wood in the
lowlands it is quite likely that it was once managed as a coppice.
This is also true for many woodlands of native broadleaves in the
uplands of southwest England, Wales, the Lake District and
western Scotland. Indeed, historians believe well over half of all
woodlands were managed by coppicing in medieval times. Yet,
today, active coppice management is confined to about 25,000 ha
or only one per cent of the total forest area.
A rapid decline in coppicing occurred in the early decades of the
last century. This arose mainly from a collapse in markets for
tanbark, charcoal, firewood, and rustic products such as thatching
spars, hurdles, and besoms. There is now something of a revival of
these rural crafts and coppicing is back in fashion along with all its
wildlife benefits.
Why restore coppice?
There are several answers to this question. First, coppicing will
bring back a neglected rural craft and demand for rustic produce
such as hazel spars, hurdles for fencing, whilst poles and sticks for
the vegetable garden are on the rise. Secondly a coppice is the
perfect renewable and sustainable energy source for firewood or
charcoal. Thirdly, and most important for many people, restoration of coppice will promote a wildlife habitat, a theme we return
to in Chapter 8.
Can a wood be too small to consider for resuming coppicing? In
a word, no. If there are clear signs that a wood was once coppiced,
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Badgers, Beeches and Blisters
even a half-acre copse (as the name implies) can be restored again,
perhaps as two quarter-acre coupes cut five years apart. If once
coppiced, it can be coppiced again.
Recognising coppice woodland
Because coppice uses the regrowth that sprouts from cut stumps,
the key to identifying that a woodland is in fact a coppice is to look
at the trees and how they appear. In a forest that is not coppiced
but felled and replanted or regenerated by natural seeding all the
trees will have single stems or trunks at ground level. In a coppice
things will be quite different. Most trees will be multi-stemmed at
or near the base with two of more trunks growing up very close to
each other.
Sometimes in a long neglected coppice one tree stem or trunk
will dominate and the others from the stump fail to grow much.
Often the dominant trunk will appear slightly bent or swept at the
base curving up a little from the ground and slightly off-centre.
This feature, and the presence of even weak basal shoots, indicate
a likely history of coppicing. A good example is the National
Trust’s lovely Hembury Woods on Dartmoor. They have been well
thinned over the last 30 years with the best trunks of coppice
origin favoured (a treatment called ‘storing coppice’) and the
woods now look like a delightful high forest of oaks. But careful
inspection of the base of each tree shows this off-centre feature of
the trunk and often several straggly shoots persisting and growing
out of the base – the sure signs of coppice origin.
Where coppicing has been practised for hundreds of years the
original stumps will have long disappeared. However, the present
trees may still be in multi-stemmed groups and also may make an
informal ring with other clumps a bit like a fairy ring of
mushrooms and toadstools. What has happened is that at each
coppicing the new shoots arise at the periphery of a stump and so
it enlarges a little each time.
Types of coppice
Coppices are not all the same. They vary in species composition, in
their rotation or length of cutting cycle, and whether or not they
have large trees (standards) scattered through them. I give a
simple classification below which I hope is helpful. Once you
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Growing and caring for trees
know the type of coppice woodland you have, then its treatment
becomes clearer.
Pure coppice This is a coppice made up of one species. Examples
include sweet chestnut, which is common in Essex, Kent and
Sussex, hornbeam on the heavy clay soils around London, hazel in
many woodlands in the southern half of Britain, and oak woods all
along the western seaboard.
Mixed coppice This is a coppice of several species and
deliberately managed as such. It is fairly common and is usually
a short rotation coppice for producing bean poles, pea sticks,
hedging stakes and similar small sized material. Mixed coppices
typically contain hazel, birch, sallow, hawthorn, ash and sometimes oak, lime, field maple, buckthorn, wild cherry and alder.
Short rotation coppice While there is no strict definition of what
is ‘short’, it is usually accepted that coppice crops cut on a cycle or
rotation of less than 10 years is short rotation, typically hazel.
However, the name has been hijacked by the energy industry as
‘short rotation coppice’, or SRC as it is sometimes called, and is
recognised today as a special crop of poplar or willow grown for
biomass or ‘green’ energy.
To be strictly accurate, we should mention osiers, where special
varieties of willow are cut each year to yield the pliable and wiry
‘withies’ for basket making. This is still an active local industry on
the Somerset Levels.
Long rotation coppice All other coppices are worked on cycles
longer than 10 years, and sometimes as long as 30 years, but rarely
more. Such coppices include sweet chestnut, cut on a rotation of
12–18 years depending on quality, and worked for fencing stakes
and traditionally hop poles, oak on a 25–30 year cycle when it was
managed for tanbark, and hornbeam a similar length of time when
it supplied firewood and charcoal for industry and the hearths of
the home counties. Other coppices managed for firewood, or even
pulpwood, would have rotations of 20–30 years to produce pole
size material.
Coppice with standards This is a coppice crop within which
there is a scattering of larger trees that stand over the coppice or
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Badgers, Beeches and Blisters
understorey (called ‘underwood’ in such circumstances). These
larger trees, called standards, are well spaced apart so that the
coppice is not heavily shaded. The idea is that both large timber
as well as small-sized produce from the coppice are obtained
from the site. Coppice-with-standards make an attractive stand
and many traditional coppice woodlands were managed in this
way.
It is easy to tell whether a woodland today is a neglected
coppice-with-standards. As well as having clumps of multistemmed trees arising from the base, the big trees present will,
very tellingly, have large usually dead branches low on the trunk.
Typically these large limbs will be only 6 or 7 m from the ground.
This shows that once these trees grew in much more open well lit
conditions and not in a dark forest stand environment, even
though today they may be in dense woodland. Part of my wood
that we call Nain’s Copse is like this with an underwood of
sycamore and ash, last cut in about 1960, and a scattering of oak
standards with only short branch-free trunks.
Standards are carefully managed along with the main coppice
crop. Each time the coppice is cut, say every 20 years, the oldest
standards will be taken and a few new young ones recruited.
Typically a coppice-with-standards will have several age classes of
standards that match the cutting cycle. Thus a coppice cut on a 20
year cycle should have a few standards each of 20, 40, 60, 80 and
perhaps 100 years old respectively. This is illustrated at the end of
Chapter 2 and again here to try and make it clear.
Coppice with standards showing different ages of standards
Oak is much the commonest species used as a standard. Ash is
also suitable, but beech and hornbeam cast too heavy shade.
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How to coppice
This is a wintertime job though it can be carried out later into the
spring than planting. Ideally coppicing should be finished by the
end of April otherwise the new shoots emerge late in the summer
and are still small by the following winter. Cut coppice stems
cleanly to near ground level taking care not to damage the bark.
Provided the area is not heavily browsed, new shoots (coppice)
emerge from the stump, called a ‘stool’, in late spring. The new
shoots may grow 4–6 ft (1–1.5 m) in the first year. Initially many
shoots will grow up but these thin themselves often to leave half-adozen by about 15 years of age or two or three times this number
in the case of hazel.
Standards can be either recruited by leaving the occasional
coppice stem or be planted.
Pollarding
The tree is regularly decapitated at intervals of 10 to 20 years and
the shoots (branches) traditionally used for firewood or stored for
winter cattle feed. The operation fell into neglect and many of
today’s large, stag-headed, multi-limbed trees are the result. Let’s
remind ourselves what pollards look like from John White’s
sketches in Chapter 2.
Different kinds of pollards
Pollarding is seeing a revival, particularly for riverside willows
and there are some attempts to resume the practice on long
neglected trees, but it is not at all easy. The trick appears to be only
to cut off the branch just above the old cut and not below and into
even older wood, but even this will not guarantee success.
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Pollarding can create very old and squat trunks, often decay
ridden, but still alive and a serviceable shell with an interior home
to highly specialised beetles and other micro-organisms. It is a
good operation to perpetuate.
Peacock butterfly with its favourite food, the stinging nettle: at home in almost all
working woodlands
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